The invention relates to road paving machines, and more particularly to a cast auger for transporting paving material from a road paving machine to a road bed.
Road paving machines are used to deposit, spread, and compact an aggregate-filled tar-based paving material onto a prepared road bed to form a hard pavement surface. The consistency of the paving material makes it difficult to maneuver the paving material from the road paving machine onto the road bed.
A typical road paving machine includes a rotating auger that acts as a screw conveyor which mixes and transports the paving material from a storage hopper on the paving machine onto the road bed. The auger includes a plurality of flight sections that are usually individually cast and then assembled together by butt welds, rivets, keys, butt straps, lap joints, dovetails, or by other conventional means. One or more of the flight sections are usually fastened to one another or a rotatable drive shaft. In an alternative form, each flight section is independently mounted to the shaft to eliminate the need to mechanically fasten the intermediate flight sections together.
During the casting process molten metal is poured through a runner and a gate to feed a cavity within a tool. This cavity is generally the shape of the desired flight section. After the metal has cooled the runner and gate are removed from the flight by a cutoff operation that leaves a gate projection (or witness) attached to the flight section. It is necessary to remove the gate projection so that there is a smooth transition between adjacent flight sections. The gate projections are typically ground flush to the surface of the flight section by using an abrasive belt or some similar device. This grinding operation is generally time consuming, costly, and labor intensive.
The above described augers are generally effective for mixing and transporting paving material from a hopper to a road bed. Therefore, any improvement in the design or manufacture of such augers would be desirable.
The present invention is directed to a cast auger for a road paving machine. The auger is rotated within the paving machine in order to mix and transport paving material from a storage hopper on the road paving machine onto a road bed.
The auger of the present invention simplifies fabrication of the auger by eliminating costly grinding operations that are associated with casting the auger. The cast auger of the present invention is also readily adapted for use in existing road paving machines.
The auger includes a first cast section and a second cast section. The first cast section includes a first flight having a gate projection that remains on the first flight after a gate which is used during casting the first cast section has been removed from the first cast section. The second cast section includes a second flight having a recess that receives the gate projection when the first flight is coupled to the second flight such that the gate projection does not need to be ground off in order to attach the first cast section to the second cast section. The first flight is attached with the second flight to create a substantially smooth and unbroken transition between the first flight and the second flight such that the auger efficiently transports paving material from the hopper of a road paving machine onto a prepared road bed.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.